4. GNSS signals

In order to calculate a position, it is necessary to understand the structure of the signals and to explain the main issues involved. The description given here is by no means exhaustive. It aims to raise awareness of the difficulties and the ways in which designers have approached the problems in order to provide some answers. The principles will be described for GPS and the differences, where applicable, will be specified for other systems.

We will only deal with GNSS here. In particular, we won't go into detail about the operation of other satellite positioning systems, such as Argos, which are based on rather different measurement concepts.